The main aim of the work in progress is to reach a better understanding of the central control of body temperature. Emphasis is placed on the control of fever, the effect of heatstroke on central temperature controls and the role of recently described putative neurotransmitters in fever and antipyresis. In each experiment the role of the primary temperature control in the preoptic/anterior hypothalamic region and of a secondary temperature control in the medulla oblongata is examined. Experiments to be carried out in the next year are based on findings of the current year: that febrile response to systemic and intracerebroventricular pyrogen persists after the primary temperature control is destroyed and that a certain putative neurotransmitter appears to have a specific role in antipyresis. The cessation of sweating in heatstroke is believed to be due to a disorder of central thermosensitive neurons and this idea will be tested in the next year. Questions have also been raised as to the depressive effect of pyrogens on thermosensitivity of the primary temperature control. These ideas will be tested in experiments using squirrel monkeys with chronic thermodes and injection cannulae, and in which heat production and heat loss responses are measured. The purpose is to develop new information about the central control of body temperature in normal and pathological states which can be eventually applied to problems in clinical neurology, neurosurgery, neuropharmacology and internal medicine. BIBLIOGRAPHIC REFERENCE: Lipton, J.M. and G.P. Trzcinka. Fever after preoptic/anterior hypothalamic lesions. Int. J. Biometeorol. (Suppl. 6) 19:24, 1975.